Spark generator and components therefor

ABSTRACT

A spark igniter for gas fired devices wherein the isolated capacitor of a diode-capacitor voltage tripler is used to store electrical charge for firing the igniter. A timer is used to fire the igniter, whereby peak line current is kept very small. A special circuit is employed to disable the timer when the gas is lit.

D United States Patent 7 [151 3,662,185 Sapir [4 1 May 9, 19 72 [54]SPARK GENERATOR AND [56] References Cited COMPONENTS THEREFOR UNITEDSTATES PATENTS lnvenwfl Said p Wesflake Village, Calif- 3,441,356 4/1969Walbridge .43 1/66 l h [73] Asslgnee' ggs fi ggz zfl sgrg v Te egrapPrimary Examiner-Herman J. Hohauser p0 Au0rne vC. Cornell Remsen, Jr.,Walter J. Baum, Paul W. [22] Filed: Oct. 1, 1970 Hemminger, Charles L.Johnson, Jr. and Thomas E. Kristof- 21 Appl. No.: 77,070

[57] ABSTRACT [52] U.S.Cl ..307/l06, 321/ l5,34037l//l6666, A Sparkigniter for g fired devices erein the isolated 51 I t I I "03k 3/00capacitor of a diode-capacitor voltage tripler is used to store S l 17 18 electrical charge for firing the igniter. A timer is used to fire307/l 19, 106, I08; 431/61, 62, 63, 64, 65, 66 X the igniter, wherebypeak line current is kept very small. A special circuit is employed todisable the timer when the gas is lit.

6 Claims, 2 Drawing Figures PATENTEDMM 9 1972 SHEEI 1 0F 2 INVENTOR Y59/0 SAP/R HTTORNE V F'A'TENTEBMM 91972 SHEET 2 [1F 2 INVENTOR.

SAID SAP/R BY 3 I ATTORNEY l SPARK GENERATOR AND COMPONENTS THEREFORBACKGROUND OF THE INVENTION This invention relates to sources ofpotential, and more particularly, to a spark generator and a voltagetripler therefor.

Although the system and voltage tripler of the present invention andcertain circuit portions thereof may be used in arts wholly unrelated tofuel ignition, the invention has been found to be especially useful inautomatically igniting natural gas emanating from a pilot burner used ina device such as a furnace or water heater in rooftop or otherinstallations in which the device is not easily accessible. Due to thewide range of application of the invention, its use is not limited toeither those described hereinbefore or hereinafter.

In the. past, spark generators for fuel ignition have frequently causedheavy current surges in the line. Such devices are disclosed in U. S.Pat. Nos. 3,349,284 and 3,377,125. Brief but frequent and heavy currentdemands can cause the line voltage to drop, to increase the averagepower consumption and to increase line losses. All of these results areundesirable.

The cost and size of prior art spark generators have also been large.

SUMMARY OF THE INVENTION In accordance with the device of the presentinvention, the

above-described and other disadvantages of the prior art are capacitor.The isolation of this capacitor reduces any current drain on the sourcewhich might otherwise occur when the capacitor is discharged duringarcing.

Another feature of the invention resides in the use of two auxiliarycapacitors smaller than the storage capacitor. The auxiliary capacitorsthus are charged by line current at a low rate and one dumps its chargeinto the storage capacitor a little at a time. Peak line current is thuskept small. A series resistor reduces charging current and peak linecurrent at the source frequency.

Another feature of the invention is the use of a timer to fire theigniter at a frequency less than the line frequency. Peak line'currentand average power are thus both reduced. The lower timerfrequencypermits the charging of the storage capacitor to a conveniently highervoltage with a low peak line current.

It is a feature of the invention that all three capacitors are combinedinto a voltage tripler to substantially reduce the size and cost of theigniter transformer. Note that the size and cost of the transformer isproportional to its turns or turns ratio, and the latter number is verylarge because an open circuit voltage of about 20 KV must be employed toreliably produce an arc across a representative 3/ 16-inch gap. Thespark, however, does appear at a lower voltage since the open circuitvoltage is measured with the transformer secondary leads much furtherapart than three-sixteenths inch. A large secondary voltage is requiredso that the igniter will have a small output rise time, will not besensitive to normal gap tolerances, and can break down any deposits thatmay accumulate on the pilot or on the electrode.

The storage capacitor thus has a dual function. It storeselectrical-charge for spark ignition. It also actually increaes 1 theoutput voltage of the multiplier from 2E to 3E.

A further feature of the invention resides in the fact that thecapacitors of the tripler actually reduce the peak line current whilethey effect the voltage boost advantage of the tripler at the same time.

It is an advantage of the invention that the supply voltage may comefrom a transformer. Prior art devices would not operate in this casebecause of the damping effect of transformer inductance on rapid changesin current. The present invention is operative in such a case becausethe storage capacitor is isolated from the source and does not dischargetherethrough.

It is a feature of the invention that peak line current is reduced. Notethat instantaneous power is proportional to iR where i is current and Ris resistance. The control of peak cur rent is thus exceptionallyimportant because instantaneous power is not merely a linear function ofcurrent, but a squared function thereof.

Another advantage of reduced peak line current is concurrent reductionin radio frequency interference (RFI) and television interference (TVI).Conductive RF] and TW are reduced because the storage capacitor and itsdischarge igniter circuit are isolated from the line. The highfrequencies generated on discharge and ignition are thus notconductively coupled to the line.

The above-described and other advantages of the invention will be betterunderstood from the following description when considered in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 in the drawing is a schematicdiagram of a spark igniter for a gas fired device.

FIG. 2 is a schematic diagram of an alternative embodiment of a voltagetripler constructed in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the igniter ofthe present invention is indicated at 10 having input terminals 11 and12 for connection of an ac supply.

Various points in the circuit include junctions. For example, junctionsare indicated at 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 and26. An input lead wire 27 is connected from terminal 11 to junction 13.A capacitor C1 is connected between junctions l3 and 14. A diode D1 isconnected between junctions 14 and 18. A diode D2 is connected betweenjunctions 14 and 15. A capacitor C2 is connected between junctions 15and 18. A lead wire 28 is connected between terminal, 12 and junction18. A capacitor C3 is connected between junctions 16 and 19.

A series circuit 29 is connected between junctions l3 and 19. Seriescircuit 29 includes a resistor R1 connected from junction 19 to theanode 30 of diode D3. The cathode 31 of diode D3 is connected tojunction 13.

Capacitor C3 is connected between junctions 16 and 19.

A pilot burner is indicated at 32. Pilot burner 32 may burn, forexample, natural gas. Pilot burner 32 includes a conduit 33 for thenatural gas having an opening 34 through which the gas emanates. The gasthus burns above opening 34.

Burner 32 also includes a shield 35 having a horizontally projecting tip36. Shield 35 may be employed as a wind guard for the frame. At the sametime, projection 36 is employed as a spark electrode.

As described, conduit 33 and guard 35 both may be conductive and may beconductively fixed together. Guard 35 may be grounded in any desiredmanner, for example, at 26. Normally, guard 35 would be grounded simplyby the way in which it is conventionally fixed in position. That is, inmost cases, it will not be necessary to take any additional steps toground guard 35.

A lead 37 connects junctions l5 and 16. A lead 38 connects junctions l6and 17. A resistor R2 is connected between junctions 17 and 20, A lead39 is connected between junctions 20 and 21. A conventional neon lamp N1is connected between junctions 21 and 22. A capacitor C4 is connectedbetween junctions 21 and 22. A resistor R4 is connected betweenjunctions 23 and 24. A lead 40 connects junctions 19 and 22. Lead 41connects junctions 22 and 24.

A transformer is indicated at T1. Transformer T1 has a primary winding42 and a secondary winding 43. A second series circuit is indicated at44 connected between junctions l7 and 24. Series circuit 44 includestransformer primary 42 and a silicon-controlled rectifier (SCR), whereinthe primary 42 is connected from junction 17 to the anode 45 of SCR CR1,the cathode 46 of the SCR CR1 being connected to junction 24. SCR CR1has a gate 47 connected to junction 23 by a lead 48.

One side of secondary 43 is connected to junction 21 by a lead 49. Theother side of secondary 43 is connected to the other spark electrode 50at junction 25 over a lead 51. insulation, which is broken away, isindicated at 52.

Spark electrode 50 may be supported in a fixed position, as shown, byany conventional means 53.

Each component part of the igniter may have the following values:

Capacitor C1 .1 microfarad, 250 volts Capacitor C2 .1 microfarad, 250volts Capacitor C3 2.2 microfarads, 250 volts Capacitor C4 .1microfarad, 200 volts Diode D4 IN 914 Diode D2 IN 914 Diode D3 IN 9l4SCR CR1 IR l06A Neon Lamp N1 Type A0 79 Resistor R1 L000 ohms ResistorR2 33 megohms Resistor R4 1,000 ohms AC Supply 24 volts, 50/60 hertzFrom the foregoing, it will be appreciated that the capacitance ofcapacitor C1 is equal to that of capacitor C2. Similarly, thecapacitance of capacitor C4 is equal to that of capacitor C1. [t is notnecessary to use these relative values for capacitors C1, C2 and C4.However, values close to these relative values are preferred. Inparticular, capacitors Cl and C2 each have to capacitance substantially.less than capacitor C3. it is the capacitor C3 which discharges throughtransformer primary 42 to create the are between spark electrodes 36-and50.

If terminal 12 first goes positive and there is no charge on capacitorC2, capacitor C2 will not charge in a direction opposite to that shownbecause the electrodes of capacitor C2 are clamped together by diodes D1and D2. Only capacitors Cl and C3 would charge with the polaritiesshown.

The transient response of capacitors C1 and C2 to charge from zerocharge if terminal 11 first goes positive is for capacitor C3 not tocharge, for capacitor C2 to charge with the polarity shown, and forcapacitor C1 to charge with the opposite polarity. However, on theimmediately succeeding half cycle of the supply voltage, capacitor C1would discharge extremely rapidly into a low supply impedance and beginto charge with the polarity shown for the following reasons.

The normal charging operation of capacitor C3 begins when terminal 12first becomes positive with respect to terminal 11. In this case,capacitor C1 charges rapidly through the source impedance to the peakpotential reached between terminals 11 and 12 through diode D1. When theac. supply voltage across terminals 11 and 12 reverses the terminal 11becomes positive with respect to terminal 12, capacitor C1 dischargesinto capacitor C2 through diode D2. Capacitor C3 receives additionalcharging while terminal 11 is positive as capacitors dischargethereinto. Charging thus continues until the peak dc. voltage acrosscapacitor C2 is approximately equal to twice the peak of the supplyvoltage. Capacitors C1 and C2 with diodes D1 and D2 form an entirelyconventional voltage doubler should circuit 29 be disconnected fromjunctions 13 and 19, and lead 37 be disconnected from junctions 15 and16.

Although the charging of capacitor C2 has been described as beingindependent of capacitor C3, it is, in fact, not independent. Forexample, each time terminal 12 becomes positive with respect to terminal11, capacitor C3 is directly placed across the line as follows. Thecircuit from terminal 12 is made through lead 28, capacitor C2,capacitor C3, series circuit 29, and lead 27 to terminal 11. Thus, whenterminal 12 is positive with respect to terminal 11, capacitor C2, if itis charged with the polarity shown, will discharge into capacitor C3.Since the voltage at terminal 12 is at E peak, and the voltage acrosscapacitor C2 is actually 2E, the peak d.c. voltage reached acrosscapacitor C3 is thus 3E.

The resistor R1 is optional. Thus anode 30 of diode D3 may be connecteddirectly to junction 19. For this reason, the said voltage doublercombined with capacitor C3 and diode D3 is a voltage tripler. ResistorR1 merely limits the charging current of capacitor C3 and thereforereduces the line current, but resistor R1 is primarily employed to limitthe discharge of capacitor C3 when it is charged with the reversepolarity. It is so charged after spark ignition because C3 withtransformer T1 acts as a tuned circuit which rings.

In accordance with the present invention, placement of spark electrodes36 and 50 in a position such that the resistance therebetween issubstantially reduced when the gas is ignited makes it possible toprevent spark ignition in that case.

When the gas is not ignited, the resistance between junction 20 andcurrent is extremely high. Capacitor C4 then charges through resistorR2. The potential of junction 21 thus rises above ground as capacitor C4charges. When the potential of junction 21 is sufficiently high, neonlamp N1 fires. When neon lamp N1 fires, SCR CR1 is gated on, andcapacitor C3 discharges. The discharge path of capacitor C3 is throughlead 38, series circuit 44, lead 41, and lead 40 to ground. Thedischarge of capacitor C3 causes an arc to be produced betweenelectrodes 36 and 50. Electrode 36 is maintained at or is at groundpotential. Note junction 26 is grounded. Current to sustain the arcwhich passes through electrode 50 and through secondary 43 to groundalso flows through lead 39 and through capacitor C4. This is truebecause the secondary current is somewhat triangular as a function oftime, ie a spike. The peak current may be 1,200 milliamperes and mayexist for about 1 microsecond. Thus a Fourier analysis of the spikewould reveal a fundamental of about 1 megahertz. At 1 megahertz, theimpedance of capacitor C4 is less than 2 ohms.

When the gas is ignited, the resistance between spark electrodes 36 and50 may be reduced to about 30 megohms. This 30-megohm resistance incombination with the 33-megohm resistance of resistor R2 acts as avoltage divider between junction 17 and ground. The dc. resistance ofsecondary 43 is negligible in comparison to the 33-megohm resistance ofresistor R2. Thus, the potential of junctions 20 and 21 are deptsufficiently low so that neon lamp N1 cannot fire.

Resistors are V2 W, 10%.

SUMMARY OF OPERATION The voltage triplet develops a dc. voltage acrosscapacitor C3 with the polarity indicated, which is about three times thepeak voltage of the supply. Capacitor C3 is charged a little bit at atime by first charging capacitor C1, then charging capacitor C2, andfinally charging capacitor C3.

As capacitor C3 charges, the potential of junction 17 rises. As thepotential of junction 17 rises, capacitor C4 charges at a greater rate,but at a rate which is also a function of the resistance of resistor R2and its own capacitance Capacitor C3 charges slowly. The chargingpotential of capacitor at junction 17 thus rises slowly. The rise in thepotential of junction 20 is even slower because it is inherent in theoperation of capacitor that it cannot change its voltageinstantaneously. The firing frequency of the SCR CR1 thus is reducedsubstantially below the ac. supply frequency by the charging ofcapacitor C4. Note also that the charging rate of capacitor C4 isdetermined by the magnitude of the resistance of resistor R2 which isvery large, Le. 33 megohms, For the foregoing reasons, neon lamp N1 maynot fire except at 3- second intervals when the supply frequency is 60hertz.

When the potential at junction 21 rises sufficiently, neon lamp N1 firesdischarging capacitor C4 through resistor R4 and raising the potentialof gate 47 until SCR CR1 fires.

When SCR CR1 fires, capacitor C3 discharges through transformer primary42, and the secondary output voltage causes an arc to be sustained for abrief time between spark electrodes 36 and 50, the ground return fortransformer secondary 43 over lead 49 being through capacitor C4.

Once the gas is ignited, the resistance between electrodes 36 and 50reduces because the gas therebetween ionizes and creates a lowerresistance path. This, therefore, keeps the potential of junction 21below the firing potential of neon lamp N1.

In accordance with the foregoing, it will be appreciated that line peakcurrent is kept small because capacitors C1 and C2 together pump in asmall charge each cycle of the line frequency into capacitor C3.Further, note that the discharge path capacitor C3 is effectivelyisolated from the a.c. supply. That is, discharge path extends throughlead 36, circuit 44, lead 41, and lead 40 to ground and is whollydisconnected from the a.c. supply. Note that the path just describeddoes not include the a.c. supply.

The invention has a timer which includes, for example, capacitor C4. Dueto the fact that the firing rate is substantially smaller than the linefrequency, additional time is provided to charge capacitor C3 to ahigher voltage with a low peak line current as well as a low averagecurrent, i.e. low power. The power consumption is directly proportionalto are frequency.

Note will be taken that the voltage tripler of the invention providesduel advantages. For example, the increase in line voltage makes itpossible to use a smaller capacitor and to use a transformer of asubstantially smaller size and of a substantially lower cost. Forexample, assume that the transformer turns ratio is to 2,000. In orderto triple the output voltage, the transformer turns ratio would have tobe increased to 10 to 6,000. Moreover, a nominal open circuit voltage of20,000 volts must be created between electrodes 36 and 50 to create anare over a distance of about three-sixteenths inch.

Note that capacitor C3 performs a dual function. It performs a voltagetripling function in the tripler, and it performs a capacitor dischargefunction in the igniter.

The combination of resistor R2 and capacitor C4 makes an extremelyinexpensive timer. Moreover, nothing need be added to bias junctiontoward ground to disable the timer except the connections of theelectrodes 36 and 50 and their placement in the flame.

Should a transformer be connected to terminals 11 and 12, the embodimentof the present invention will operate without difficulty. This is truebecause the discharge path of capacitor C3 is not through the a.c.supply. Such a transformer cannot be used in the device disclosed in theaforementioned patent. This is true because the capacitor discharge inthe device of said patent is through the a.c. supply. In such a case, aninput transformer would present an extremely high impedance to the aregenerating current and would prevent the are from being produced at anytime.

It is a special feature of the invention that peak current in the lineis reduced because instantaneous power is directly proportional to thesquare of current. A reduction in peak current thus provides a markedreduction in power.

As stated previously, the discharge of capacitor C3 through primary 42and not through a.c. supply provides the reduction of RF] and TVI peakinto the line. Note will be taken that there are several features of theinvention disclosed herein that may be used in this and other arts. Eachfeature of the invention may be used in any combination with any of theother features or by itself.

As stated previously, resistor R1 may be omitted. The voltage triplermay be used by itself. The timer may be used by itself. If no automatictimer shutdown is desired or required, lead 49 may be disconnected fromjunction 20 and connected directly to ground. The location of sparkelectrodes 36 and 50 is thus less important.

Any voltage breakdown device may be used for neon lamp N. If, forexample, a trigger diode replaced neon lamp N1, an additional resistormight be connected between junctions 20 and 22.

THE ALTERNATIVE EMBODIMENT OF FIG. 2

An alternative embodiment of the voltage tripler of the presentinvention is indicated at 54 in FIG. 2.

As before, tripler 54 has various junctions 55, 56, 57, 58, 59, 60, 61and 62. Tripler 54 has input leads 63 and 64, and output leads 65 and66.

Tripler 54 may replace the voltage tripler of FIG. 1. For example, leads38 and 40 may be disconnected from junctions l7 and 22, respectively,and leads 65 and 66 connected thereto, respectively.

In the circuit of FIG. 2, three terminals 67, 68 and 69 are provided. Aresistor 70 is connected from terminal 67 to junction 55. Terminal 68 isalso connected to junction 55. Terminal 69 is connected to junction 56.A resistor 71 is connected between junctions 55 and 56.

If leads 63 and 64 are broken so that they do not touch junctions 55 and56, only the right-hand portion of the circuit comprises the tripler 54,all of the structure on the left side thereof being simply inputapparatus which may or may not be used, as desired. Specifically,resistors 70 and 71 form a voltage divider so that alternatively l20volts may be applied between terminals 67 and 69, or 24 volts may beapplied between terminals 68 and 69.

A resistor 72 is connected between junctions 55 and 57. A diode 73 isconnected between junctions 57 and 58. A diode 74 is connected betweenjunctions 58 and 59. A capacitor 75 is connected between junctions 57and 59. A diode 76 is connected between junctions 59 and 61. A capacitor77 is connected between junctions 61 and 62, junction 62 being groundedin the manner that junction 19 in FIG. 1 is also grounded. A lead wire78 is connected between junctions 60 v and 62. A capacitor 79 isconnected between junctions 58 and 60.

Tripler 54 may appear to be strikingly different from the tripler shownin FIG. 1, however, tripler 54 is in fact very similar to the tripler inFIG. 1, and the operation of the tripler 54 is substantially identicalto that of the tripler shown in FIG. 1. For example, all of the commoncircuit elements may have identical values. What is meant by common" arethose analogous circuit elements. For example, capacitor 79 may beidentical to capacitor C1 in size and in all other respects. That is,the capacitance of capacitor 79 may be identical to the capacitance ofcapacitor C1. Similarly, capacitor 75 may be identical to capacitor C2and capacitor 77 may be identical to capacitor C3.

One change in tripler 54, it will be noted, is that lead 27 of FIG. 1has been replaced with lead 64 and placed on the bottom of the figureand grounded at junction 62. However, with this and two otherexceptions, the tripler of FIG. 2 is identical to the tripler of FIG. I.

One of the two other exceptions is that resistor 72 may be identical toresistor R] but is located in a different position. Diode 76 may also beidentical to diode D3, but it too is located in a different position.Thus, the location of diode 76 is the other one of the said twoexceptions.

When the word identicaP is used herein, this word is hereby defined forsuch use as meaning at least that the resistance of resistor 72 isidentical to the resistance of resistor R1, and that the capacitances ofcapacitors 79, 75 and 77 are identical to the capacitance of capacitorsC1, C2 and C3, respectively.

The tripler of FIG. 2 is advantageous in one respect over the tripler inFIG. 1 in that by placing resistor 72 and diode 76 in the ungroundedside, a short existing between leads 63 and 64 or any extension thereofto the left, as shown in FIG. 2, will not cause resistor 72 and diode 76to burn out.

The phrase means to supply an alternating input voltage and the phrase acircuit to supply an alternating input voltage" are hereby defined foruse herein and in the claims to mean an a.c. source of potential or onlyinput lead wires without an a.c. source of potential connected theretoor otherwise.

For use herein, the symbol T is hereby defined as the period of timewhich is required to store a predetermined maximum amount of energy incapacitor C3 or in capacitor 77. The maximum amount of energy stored maybe equal to or less than 1% CH where C is the capacitance of capacitorC3 or the capacitance of capacitor 77, and E is the maximum voltageacross capacitor C3 or the maximum voltage across capacitor 77 when thelamp N1 is never fired.

The maximum amount of energy'stored will depend upon theresistance-capacitance time constant of resistor R2 and capacitor C4.

For use herein, the symbol T is hereby defined as T= l/f, where f is thefrequency of the input voltage.

According to the foregoing, it is one outstanding advantage of thepresent invention that capacitors C3 and 77 charge slowly because theyare charged by the smaller capacitors C1, C2, 75 and 79. This causes alow even current drain on the source of the potential. This is madepossible because the resistor R2 and the capacitor C4 provide a timingmechanism to fire the SCR CR1 at a frequency force less than linefrequenm"- Restated, capacitors C3 and 77 charge slowly to reduce theline current load, and resistor R2 and capacitor C4 act to allow theslow charging. Thus, although T is larger than T, the firing frequencyproduced by resistor R2 and capacitor C4 is always less than the linefrequency and accommodates the lower charging period for capacitors C3and 77.

It may be of some help in understanding this invention to know of someprior art which is different from this invention. For example, voltagetriplers broadly, not of the kind of the present invention, arewell-known in the art. However, such voltage triplers have never beencombined with a spark igniter circuit. One such voltage tripler may bedescribed in connection with FIG. 1 herein. Thus, assuming all thestructure to the right of junctions 19 is removed in FIG. 1, the priorart voltage tripler would be arrived at by disconnecting the upperelectrode of capacitor C3 from junction 16, and then connecting it tojunction 18, and replacing resistor R1 with a conductive lead. Inaddition to the U. S. patents previously cited, U. 8. Pat. Nos.2,799,809; 3,045,l48; and 3,004,184 may be considered of interest eventhough different from the circuits and other structures disclosedherein.

Either embodiment of the voltage tripler of the present invention or anyother embodiment thereof may be employed in a voltage quadrupler orother voltage multiplier for producing a dc. output voltage larger thanthree times the peak input voltage.

What is claimed is:

l. A voltage multiplier comprising: first and second input leads; afirst capacitor having one electrode connected to said first input lead;first and second diodes, each of said first and second diodes having ananode and a cathode, the anode of said first diode being connected fromsaid second input lead, the other electrode of said first capacitorbeing connected to the cathode of said first diode, the anode of saidsecond diode being connected to said first diode cathode; a secondcapacitor connected from said first diode anode to said second diodecathode; and a series circuit connected from said second diode cathodeto said first input lead, said series circuit including a third diodeand a third capacitor connected in series, said diode being poled to beconductive in a direction toward said first input lead.

2. The invention as defined in claim 1, wherein said third diode has ananode and a cathode, said third diode anode being connected to oneelectrode of said third capacitor, said third diode cathode beingconnected to said first input lead, the other electrode of said thirdcapacitor being connected to said second diode cathode.

3. The invention as defined in claim I, wherein said third diode has ananode and a cathode, said third diode anode being connected to saidsecond diode cathode, said third capacitor having one electrodeconnected to said third diode cathode, and another electrode connectedto said first lead.

4. A pulse generator comprising: first means to supply an alternatinginput voltage; second means connected from said first means, said secondmeans including an electrical energy storage device, said second meansbeing actuable to store a predetermined maximum amount of energy in saiddevice but only at a rate such that said maximum amount is stored over aperiod of time, T,,, such that T, is larger than T, where T= l/f, and fis the frequency of said input voltage; third means connected to saiddevice, said third means being actuable to discharge said device rapidlyand repeatedly over time intervals small in comparison to T, said thirdmeans being actuable to discharge said device at a frequency which isless than f, said third means including a spark igniter for the pilotlight of a gas-fired appliance; said second means being a voltagemultiplier, said device being a first capacitor, said third means beingconnected in parallel with said capacitor, said multiplier including asecond capacitor actuable charge said first capacitor only on alternatehalf cycles of said input voltage, said second capacitor being connectedto be recharged periodically, said first capacitor having a capacitancelarge in comparison to that of said second capacitor.

5. A pulse generator comprising: first means to supply an alternatinginput voltage; second means connected from said first means, said secondmeans including an electrical energy storage device, said second meansbeing actuable to store a predetermined maximum amount of energy in saiddevice but only at a rate such that said maximum amount is stored over aperiod of time, T,,, such that T is larger than T, where T= l/f, and fis the frequency of said input voltage; third means connected to saiddevice, said third means being actuable to discharge said device rapidlyand repeatedly over time internals small in comparison to T, said thirdmeans being actuable to discharge said device at a frequency which isless than f; said first means including first and second input leads,said second means including a first resistor, first and secondcapacitors and first, second and third diodes, each of said diodeshaving an anode and a cathode, said electrical energy storage devicebeing a third capacitor, said first resistor being connected from saidsecond input lead to said first diode anode, said second diode anodebeing connected to said first diode cathode, said third diode and anodebeing connected to said second diode cathode, said third capacitor beingconnected from said third diode cathode to said first input lead, saidsecond capacitor being connected from said first diode anode to saidthird diode anode, said first capacitor being connected from said firstinput lead to said second diode anode, said third means including atransformer having a primary winding and a secondary winding, asilicon-controlled rectifier having an anode, a cathode and a gate, saidprimary winding having one end connected to said third diode cathode,and its other end connected to said silicon-controlled rectifier anode,said silicon-controlled rectifier cathode being connected to said firstinput lead, a second resistor having one end connected to said thirddiode cathode, a fourth capacitor having one electrode connected to theother end of said second resistor, and its other electrode connected tosaid first input lead, a neon lamp connected from said other end of saidsecond resistor to said gate, a third resistor connected from said gateto said first input lead, a pilot burner having an orifice to allow theemission of a combustible gas, two spaced spark electrodes located in aposition relative to said orifice to lie approximately within any flamecreated by the combustion of gas emanating from said orifice, saidtransformer secondary winding having one end connected to one of saidspark electrodes, and its other end connected to said other end of saidsecond resistor, the other spark electrode being connected to said firstinput lead, said third capacitor having a capacitance in excess oftwenty times that of said first capacitor, said third capacitor having acapacitance in excess of twenty times that of said second capacitor.

6. A pulse generator comprising: first means to supply an alternatinginput voltage; second means connected from said first means, said secondmeans including an electrical energy storage device, said second meansbeing actuable to store a predetermined maximum amount of energy in saiddevice but being a first capacitor, said third means being connected inparallel with said capacitor, said multiplier including a secondcapacitor actuable charge said first capacitor only on alternate halfcycles of said input voltage, said second capacitor being connected tobe recharged periodically, said first capacitor having a capacitancelarge in comparison to that of said second capacitor.

1. A voltage multiplier comprising: first and second input leads; afirst capacitor having one electrode connected to said first input lead;first and second diodes, each of said first and second diodes having ananode and a cathode, the anode of said first diode being connected fromsaid second input lead, the other electrode of said first capacitorbeing connected to the cathode of said first diode, the anode of saidsecond diode being connected to said first diode cathode; a secondcapacitor connected from said first diode anode to said second diodecathode; and a series circuit connected from said second diode cathodeto said first input lead, said series circuit including a third diodeand a third capacitor connected in series, said diode being poled to beconductive in a direction toward said first input lead.
 2. The inventionas defined in claim 1, wherein said third diode has an anode and acathode, said third diode anode being connected to one electrode of saidthird capacitor, said third diode cathode being connected to said firstinput lead, the other electrode of said third capacitor being connectedto said second diode cathode.
 3. The invention as defined in claim 1,wherein said third diode has an anode and a cathode, said third diodeanode being connected to said second diode cathode, said third capacitorhaving one electrode connected to said third diode cathode, and anotherelectrode connected to said first lead.
 4. A pulse generator comprising:first means to supply an alternating input voltage; second meansconnected from said first means, said second means including anelectrical energy storage device, said second means being actuable tostore a predetermined maximum amount of energy in said device but onlyat a rate such that said maximum amount is stored over a period of time,To, such that To is larger than T, where T 1/f, and f is the frequencyof said input voltage; third means connected to said device, said thirdmeans being actuable to discharge said device rapidly and repeatedlyover time intervals small in comparison to T, said third means beingactuable to discharge said device at a frequency which is less than f,said third means including a spark igniter for the pilot light of agas-fired appliance; said second means being a voltage multiplier, saiddevice being a first capacitor, said third means being connected inparallel with said capacitor, said multiplier including a secondcapacitor actuable charge said first capacitor only on alternate halfcycles of said input voltage, said second capacitor being connected tobe recharged periodically, said first capacitor having a capacitancelarge in comparison to that of said second capacitor.
 5. A pulsegenerator comprising: first means to supply an alternating inputvoltage; second means connected from said first means, said second meansincluding an electrical energy storage device, said second means beingactuable to store a predetermined maximum amount of energy in saiddevice but only at a rate such that said maximum amount is stored over aperiod of time, To, such that T0 is larger than T, where T 1/f, and f isthe frequency of said input voltage; third means connected to saiddevice, said third means being actuable to discharge said device rapidlyand repeatedly over time internals small in comparison to T, said thirdmeans being actuable to discharge said device at a frequency which isless than f; said first means including first and second input leads,said second means including a first resistor, first and secondcapacitors and first, second and third diodes, each of said diodeshaving an anode and a cathode, said electrical energy storage devicebeing a third capacitor, said first resistor being connected from saidsecond input lead to said first diode anode, said second diode anodebeing connected to said first diode cathode, said third diode and anodebeing connected to said second diode cathode, said third capacitor beingconnected from said third diode cathode to said first input lead, saidsecond capacitor being connected from said first diode anode to saidthird diode anode, said first capacitor being connected from said firstinput lead to said second diode anode, said third means including atransformer having a primary winding and a secondary winding, asilicon-controlled rectifier having an anode, a cathode and a gate, saidprimary winding having one end connected to said third diode cathode,and its other end connected to said silicon-controlled rectifier anode,said silicon-controlled rectifier cathode being connected to said firstinput lead, a second resistor having one end connected to said thirddiode cathode, a fourth capacitor having one electrode connected to theother end of said second resistor, and its other electrode connected tosaid first input lead, a neon lamp connected from said other end of saidsecond resistor to said gate, a third resistor connected from said gateto said first input lead, a pilot burner having an orifice to allow theemission of a combustible gas, two spaced spark electrodes located in aposition relative to said orifice to lie approximately within any flamecreated by the combustion of gas emanating from said orifice, saidtransformer secondary winding having one end connected to one of saidspark electrodes, and its other end connected to said other end of saidsecond resistor, the other spark electrode being connected to said firstinput lead, said third capacitor having a capacitance in excess oftwenty times that of said first capacitor, said third capacitor having acapacitance in excess of twenty times that of said second capacitor. 6.A pulse generator comprising: first means to supply an alternating inputvoltage; second means connected from said first means, said second meansincluding an electrical energy storage device, said second means beingactuable to store a predetermined maximum amount of energy in saiddevice but only at a rate such that said maximum amount is stored over aperiod of time, To, such that To is larger than T, where T 1/f, and f isthe frequency of said input voltage; third means connected to saiddevice, said third means being actuable to discharge said device rapidlyand repeatedly over time intervals small in comparison to T, said thirdmeans being actuable to discharge said device at a frequency which isless than f; said second means being a voltage multiplier, said devicebeing a first capacitor, said third means being connected in parallelwith said capacitor, said multiplier including a second capacitoractuable charge said first capacitor only on alternate half cycles ofsaid input voltage, said second capacitor being connected to berecharged periodically, said first capacitor having a capacitance largein comparison to that of said second capacitor.